Automatic wood-burning heater



Sept. 12, 1944. c. BARNES 2,358,044

AUTOMATIC WOOD-BURNING HEATER Filed April 1, 1941 3 Sheets-Sheet 1 3r If fi y;

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(IttornegSr Sept. 12, 1944. BARNES 4 AUTOMATIC WOOD-BURNING HEATER Filed April 1; 1941 s Sheets-Sheet 2 J C fiariwr (Itt megs! Sept. 12, 1944. J.'.c. BARNES 7 2,358,044

AUTOMATIC WOOD-BURNING HEATER Filed April 1, 1941 3 Sheets-Sheet 3 Fig.7.

(IttorncgSZ Patented Sept. 12, 1944 UNITED STATES PATENT HQFF'I'CE' 2,358jll44' AUTOMATIC WOOD-BURNING HEATER Julius C. Barnes, Columbus, Ga., 'assignor' to Columbus Iron Works 00., Columbus, Gaz, a

corporation of Georgia"- Application Aprill, 1941, Serial:No; 386,3231

in the air flow t the combustion chamber is improved in that entering air is distributed over the entire, or a large portion, of the bottom of the stove, and in which the stove is improved in: a variety of other aspects as will more fully hereinafter appear.

An object of the invention is to provide an improved heater front which involves a detachable door section removable to give access to the firebox and ash pit for the raking or removal of ashes therefrom, with meansfor quickly securing the removable door of. the front in place, and in which such door provides an air channel tothe ash pit and carries a hand-adjusted register; and an automatic damper forcontrolling. theinlet of air to such ash pit and thehollowcones.

With the foregoing. and other objects in -view, the invention will be more fully described; heremeet-may with-a cast, bottom, [0; and; cast. top H, steel sheet sides. l2. and.- usual smoke. collar [3- atthe rear of. the top. The top H supports the. swinging door; or lid, M: which. opens to permit; firing of the heater with wood;

, Inaccordance with the invention, and as best seen... in Figures 7 and 9 the. cast iron bottom [0 ismade of; an increased; depth and of an upper section: l.5and. av lower section Hi. The lower section I6 is. stepped, in from the. upper section 1.5. and in. consequence of) this construction a ledge or. shoulder I1 is formed between the sections or. rims l5 and, I6, such ledge or shoulder forming internally aseat and.v a seal for the grate H! that the rim section I5 isv cast, or otherwise proinafter and more particularly pointedout in the;

Figure 1 is a side elevation of an improved H1 7 grate space circumscribed by the stiffener rim automatic wood-burning stove constructed inaccordance with the present invention.

- Figure 2 is a fragmentary front elevation, on an enlarged scale, of the same showing; the improved stove front.

Figure 3 is a vertical section taken on: theline 33 in Figure 1. 5 v Figure 4 is also a vertical section taken on the line 44 in Figure 1.

Figure 5 is a rear elevation of the heater front unit as removed from the heater. I

Figure 6 is a horizontal section taken. on the line 66 in Figure 1.

Figure 7 is a vertical section taken on the line 11 of Figure 6.

Figure 8 is a horizontal section taken on the duced; on the section of an inverted cone. In otherwordsthe upper section or rim I5 is frustoconical; with the tapering wall converging downwardly; and in this respect it agrees With the taper given to the upstanding rim I 9 of the rate [8; 'By this sloping or tapering construction of the parts l5 and t9. suchparts form a close fit anda substantially air-tight seal; at the same time thegrate l8 is easily lifted up from the sloping wall 15 and removed when desired. 5

The grate I8; is preferably a substantially fiat casting in which the rim l9" may be' described as small comparatively in vertical height. and acts in the capacity of 'a stiffener.

H! are a plurality of raised cones 20 preferably equally distributed over' the bottom area of the heater. The purpose of the grate I8 is t'ocarry and support the woodifuel'on itsupper side, that is upon the truncated ap'eXes of the cones 20', which allow protective wood ash to settle upon the bottom of. the grate aroundand between the raised cones 20', thereby preventing excess heating and possible breaking of'the grates. Such cones are hollowwitli'their wide'bases communieating with the air space inthe ash pit 22 below and" with their upper open truncated ends forming. air passages 23communicatin'g with the combustion chamber above the grate IB: These cones constitute air inlets which serve to distribute the air evenly andin that way to promote combustion throughout the area of the bottom, resulting'in evenand complete consumption of fuel.

In, theconventional stove such is not the case where the air enters at one.point at the front passing over the fire and out the stack.

Another important purpose of the cones 20 is Within the V damper.

1 to keep as large apercen'tage of ash as possible on top of the grate l8 and a minimum from falling through to the bottom 24 below. Such construction serves to keep open the air passage under the two planes, the upper for firing and the lower.

for air entry and distribution. On the front of the heater, the cast bottom and the steel sheet side 12 of the heaterare cut away and a double of the door in both directions. on the inner projecting end of the rod 48 there is carried a coiled or volute bimetallic thermostat 49, the inner end of which is afiixed to the rod 48 while the outer end of the thermostat is secured to an arm 50 fastened to the damper 41, which arm plays through an arcuate slot 5|. in the rear wall 3| of the door.

- The outer end of the rod 48 'isfashioned into, or connected with, a crank 52 having its outer end threaded to receive a knurled nut 53. The

"crank ,52 plays through a slot 54 in a register door frame 25 is bolted, or otherwise secured, to

' the heater at this point.

'As best seen in Figures 7 and 9, the cut away portion which is covered by the door frame 25 provides two openings 26 and 21. 26 is above the opening 21. The upper opening 26' communicates witha combustion space above the grate l8 and permits the removal of ash from the tops of the cones 20. The lower opening permits the removal of any ash that drops through the openings 23 in the cones 20. Both openings 7 2B and 2'! are adapted for the entry of a soot or ash rake for removing ashes. The lower opening 21 also serves as a passage through which all of the 'air to the cones must pass.

The horizontal web 28 in the door frame 25 separates thedoor frame into upper and lower passages 29 and which communicate respectively with the openings 26 and 21. The door which seals the two openings 29 and 30 is made in two parts.

Such parts comprise the inner Vertical fiat wall 3| and the outer flat vertical wall 32 spaced outwardly from the inner wall 3|. The outer wall 32 carries sides 33, a top 34 and a curved bottom 35. The raised rims 36 and 31 stand outwardly from the inner wall 3| to form seats for the edges of the sides 33, top 34 and curved bottom of the outer section 32 of the door. The edges ofthe outer section which en- The opening volute bimetallic thermostat.

plate 55 bolted to the front side of the door wall 32. By loosening the nut 53 the crank 52 and rod 48 maybe rotated in one or the other direction to increase or decrease the tension on the After adjustment the nut 53 is tightened against the register plate the top side of the grate 3 down to a level of gage rims 36 and 31 may be ground to form a.

ground joint. This construction permits the outer door section, composed of outer wall 32,

double door and the airspace within the ash pit 22. The outerv member32 of the double door may be formed with enlargements or bosses" with screw' sockets to take the screws, bolts or other fastenings 4|, which pass through from the back through the inner door wall 3|.

The door carries a register and an automatic The register consistsof slots 42 made in the outer wall 32 and similar slots 43 in a shiftable register plate 44. A hand knob 45 on the register plate 44 projects out through an arcuate slot 46 in the front wall 32 for conducting the manual operation of the register 'to control the passage of the air from the external I atmosphere into the chamber of the hollow door.

The door also carries a damper 41 in its hollow chamber, the damper being supported by, and freely, rotatable around a rod 48. .The rod 48 is journaled in the inner and outer walls 3| and 55 which maintains the angle of adjustment. Such angle of adjustment may extend through 90 The damper, thermostat and adjusting device are all more fullydescribed and claimed in my copending application entitled Attachments for stoves, Serial No. 379,361, filed February 17, 1941, now abandoned.

The door is mounted in'place preferably by a hinge construction in which lugs 56 on the door frame 25 co-act with lugs 51 on the door to intermesh and receive a 'pintle or hingebolt 58.

As best seen in Figure 6, the lugs 51 on the door are made with round holes to snugly fit around the hinge bolt 58 while the'lugs 56 on the door frame are made with slots ,59. to, allow V ofi-play of the hinge bolt thereinin a direction toward and from the heater. 'This arrangement allows the door to be drawn tightly against the door frame Without binding on the hinge'bolt 58. The door is drawn tightly against the door frame by a locking key 60. Such key carries a knob Bl on its outer end and a latch lug 62 on' its inner end. The locking key 60 is rotatably mounted through the two members 32 and 3| of the door whereby the latch lug -62 may be rotated into and out of engagement with'a' rib B3 on the door frame 25. This rib 63 projects down from the web or partition 28. vided with an inclined inner face and the latch lug 62 rides such inclination, drawing the door tightly against the frame.

In operation, the register plate 44 may be moved to any desired position to shut off the entry of air to the chamber within the double door; or such register may be moved to a fully open position wherethe slots 42 and 43 register fully and completely; or the register 44 may be moved to any intermediate position providing any desired port area at the slots 42 and 43, thus restricting to a desired extent the volume of air permitted entry to the chamber- 0f the double door, and thus manually regulating the volume of air permitted to enter the ash pit and the combustion chamber of the heater. Normally the register will be moved to wide open position, and a fire started in the heater on the grate l8, the fuel being fed. through the-swinging top door I4 of the heater.

Air enters through the register into the chamber of the double door and passes the bimetallicoperated damper 41. This damper 41 is in the fully open position when cold. The fully open position is the vertical position of the damper such as shown in Figure 4. The fully closed position of the damper is shown'indotted lines in Figure 3 where the left wing of the damper 32 0f the d r, wit its ends P j n eXteriOrlY is shown as in contacting relation with the under- The rib is proof a web 65. The webs B4 and 6&1 project inwardly toward one another from the. side walls.-

33 of the hollow doorand, constitute stops for the damper 41 and also sealing means cooperating with the damper in its closed position to shut off the passage of air into the heater. When the damper 41 is cold and in the wide open position, air is admitted downwardly through the chamber in the door through openings 39 and 30 and into the ash pit 22, thus gaining access to the air passages 23 in the cones 20. Such air will be drawn upwardly by the draft through the open upper ends of the cones and into the firebox or combustion chamber, and promotes the combustion in the heater. The cone passages 23 admit this combustion-supporting air in small jets or streams at a great number of points distributed over the area of the combustion chamber so that combustion is supported and promoted in all parts of such chamber, causing the fire to burn in all parts of the heater and not locating in any one place. The arrangement tends to a uniform fire and rate of combustion throughout all horizontal parts of the combustion chamber, and tends to completely consum all of the fuel in all parts of the stove.

As the heater becomes heated, the bimetallic thermostat 49 begins to unwind or uncoil, and in so doing rotates the damper 41 with it, until, on maximum heat for which the device has been set, the thermostat expands to a point where the damper 41 is completely closed against the stop webs 64 and 65. In this position, air to the heater is completely shut off and combustion therefore lags. A mean temperature will be reached where the damper 41 is balanced and acts automatically to feed the correct amount of air to the fuel in accordance with predetermined requirements.

The ashes for the most part, will accumulate on top of the grate [8; that is to say, above the bottom wall 2! of the grate and surrounding the cones 20. Of course, during use of the stove the ashes will accumulate in great quantities high above the grate and the tops of the cones 20. The excess of the ash, meaning that quantity lying above the tops of the cones 20, will be removed when the heater is cold, such removal being accomplished by swinging the door open. As a, preliminary to the opening of the door, the latch must be unfastened which is achieved by rotating the button or nob 6|, releasing the latch.

lug 82 from the rib 63. Thus the double door is free to swing open on its hinges, exposing the openings 26 and 21. A soot rake is employed to rake the ash from the top side of the grate I8 and also from the underside of the grate.

Referring more particularly to Figures 8 and 9, such figures show a modification in that instead of the cones 20 having the round passages 23, elongated slots 23 extend through elongated raised necks 20*. This modification functions in the same way as the cones 20 except that it allows for a greater area of entrance air and would also allow ash in greater quantities to drop through the grate. It will be appreciated that the larger percentage of ash is carried on the top of the grate l8 for only a minimum percentage is allowed to drop through to the ash pit 22. This differs sharply from the conventional type of flat slotted grate bars. Such construction has the advantage of preventing burning out of the grates and; contributes to; long life in the grates,

W-here theunderside of the grate is kept clean the grate willnot burn out. On the other hand.

if hot; ashes are allowed to pile up under the grateaswellas ,on top of the grate, rapid burning out, of the grate will result. 'While the in-. vention avoidsthisdisadvantage by the same con-.

struction it secures the double function of evenly distributing the air to the fuel. Even distribution of air to the fuel will protect the sheet metal sides 22 of the heater; and in this respect the invention further differs from the conventional type of heater of this class where all the air enters at the front of the heater and causes the sheet at the front directly over the air opening to become excessively hot, resulting in short life to the steelat this point.

It will be appreciated that complete combustion is obtained according to the invention. The even and uniform distribution of air from the underside of the grate will cause the complete reduction of all the fuel to ash without an accumulation of charcoal. With the usual heater of this type, when the wood is consumed there is a distinct tendency for a gradual accumulation of charcoal, all caused from a lack of oxygen passing through the fuel bed; because the air entering through a hole in the front sheet passes upwardly and over the top of the fuel and thence out the stack, which leaves a dead air space in the back of the heater in the bottom thereof. Such dead air space starts the charcoal formation, and charcoal continues to accumulate until it is either removed or burned by constant stirring over a period of time.

It will also be appreciated that the thermostatically controlled air supply contributes with the perforated grate to a managed and governed supply of air in pro-determined volume simultaneously to all parts of the combustion space by use of the adjusting nut 53 or other adjusting device for the thermostat 49. This volume of air may be nicely controlled and the fire at all points of the firebox regulated simultaneously from this single point at the nut 53. At the same time what might be called either a primary or a secondary control is provided for through the register at the single point of the knob 45. The knob 45 and nut 53 are grouped in juxtaposition for convenient use which is important for making empirical relative adjustments of the two air governors with respect to each other to bring about the best results in the burning of any particular type of fuel under any particular type of climatic, atmospheric or other circumstances.

Although I have for convenience described the raised portions of the grate as cones 20 due to the convenient geometrical form illustrated, I wish it understood that these raised necks may be of any other form desired, for instance, the form shown in Figures 8 and 9.

It is obvious that various changes and modifications may be made in the details of construction and design of the above specifically described embodiment of this invention without departing from the spirit thereof, such changes and modifications being restricted only by the scope of the following claim.

What is claimed is:

In a heater, an ash pit, a grate above the ash pit, a door to the ash pit comprising front and back separated walls, said front wall carrying sides, a top and a bottom fitting at their free edges against said back wall, means on the back wall for centering said top, sides and bottom walls, means between said sides, top and bottom and the back Wall forrholding all of said walls together in unitary assembly for forming an air, chamber there within in constant open communi cation with the ash'pit when the door is-c'losed;

an air intake inthe upper portion of the-door; a damper carried by the door in said chamber, 7 

